A famous climber known as the 'Swiss Machine' was killed while training near Mount Everest

Ueli Steck, a famous mountain climber known as the "Swiss Machine," was killed Sunday in a mountaineering accident near Mount Everest in Nepal.

The 40-year-old, best known for his rapid ascents, was training to climb 29,035-foot Mount Everest and nearby Mount Lhotse, according to the BBC. Although the exact circumstances of his death are still unclear, the Himalayan Times wrote that he was seen climbing near the Nuptse Face of Mount Everest and may have "slipped and fell on the ice-covered slope."

Just last week, he posted this update while pursuing “active acclimatization.”

Steck's body was recovered and taken to the only airport near Mount Everest in Lukla.

"The family is infinitely sad and asks that the media refrain from speculating about his death out of respect and consideration for Ueli," a statement on Steck's Facebook page said. "As soon as reliable information about Ueli Steck’s death becomes available, the media will be informed."

Steck is the first casualty in the spring mountaineering season, which began in March and lasts until the end of May.